Paulownia tree named ‘WEGROW-B6’

ABSTRACT

A new and distinct  Paulownia  hybrid tree named ‘WEGROW-B6’ which is characterized by an upright trunk, fast vertical rate of growth, high frost resistance, and earlier flowering, and the stability of these characteristics from generation to generation.

Latin name of the genus and species: The Latin name of the genus and species of the novel variety disclosed herein is Paulownia hybrid.

Variety denomination: The inventive variety of Paulownia hybrid disclosed herein has been given the variety denomination ‘WEGROW-B6’.

BACKGROUND OF THE INVENTION

Parentage: The claimed tree is a seedling selection resulting from the controlled crosspollination of an unnamed Paulownia elongata S.Y. Hu tree (not patented), the seed parent, with an unnamed Paulownia fortunei Hemsl. tree (not patented), the pollen parent, at a tree plantation established at the experimental field of the University of Bonn in Rheinbach, Germany. In summer of 2014, after one year of cultivation, one tree growing amongst a population of 60 trees originating from the crossing in 2010 was observed to exhibit a faster rate of growth, early flowering initiation, and improved frost tolerance relative to other progeny and the parent plants. The tree was isolated for further evaluation in order to confirm the distinctness and stability of the characteristics first observed. In the summer of 2017, upon confirmation of distinctness and stability, ‘WEGROW-B6’ was selected for commercialization.

Asexual Reproduction: In the summer of 2016, ‘WEGROW-B6’ was first asexually reproduced by way of meristematic tissue culture micropropagation in Tönisvorst, Germany. The claimed tree was found to asexually reproduce in a uniform and stable manner and successive cycles of vegetative propagation have proven to be true to type.

SUMMARY OF THE INVENTION

The cultivar ‘WEGROW-B6’ has not been observed under all possible environmental conditions. The phenotype may vary somewhat with variations in environment such as temperature, day length, and light intensity, without, however, any variance in genotype. The following traits have been repeatedly observed and are determined to be the unique characteristics of ‘WEGROW-B6’. These characteristics in combination distinguish ‘WEGROW-B6’ as a new and distinct Paulownia tree:

-   -   1. ‘WEGROW-B6’ exhibits a fast rate of growth with an upright         trunk that rapidly increases in diameter and height which, when         cultivated for timber production, equates to greater         productivity; and     -   2. ‘WEGROW-B6’ exhibits a high degree of frost tolerance and         cold hardiness to minus twenty-two degrees Celsius; and     -   3. ‘WEGROW-B6’ exhibits a strong homogenous stem development;         and     -   4. ‘WEGROW-B6’ exhibits early flower initiation, with flower bud         development beginning in late September and flowers opening in         late March of the following year in Rheinbach, Germany.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates, as nearly true as it is reasonably possible to make the same in color photographs of this type, a field-grown ‘WEGROW-B6’ tree at approximately 3.5 years of age, during spring in Tönisvorst, Germany.

FIG. 2 illustrates, as nearly true as it is reasonably possible to make the same in color photographs of this type, the exemplary mature foliage of ‘WEGROW-B6’.

FIG. 3 illustrates, as nearly true as it is reasonably possible to make the same in color photographs of this type, the oldest wood of a mature field-grown ‘WEGROW-B6’ tree.

FIG. 4 illustrates, as nearly true as it is reasonably possible to make the same in color photographs of this type, the typical inflorescence of ‘WEGROW-B6’.

FIG. 5 illustrates, as nearly true as it is reasonably possible to make the same in color photographs of this type, the typical flowers of ‘WEGROW-B6’.

BOTANICAL DESCRIPTION OF THE PLANT

The following is a detailed botanical description of a new and distinct Paulownia hybrid plant known as ‘WEGROW-B6’. Plant observations were made on a 3.5 year-old field-grown tree in Tönisvorst, Germany. The observed tree was grown in full exposure to natural sunlight, and maintained with drip irrigation. No pest or pathogen countermeasures were employed. Two years after planting the observed tree into the field, the tree was pruned to the soil level in May of 2019 and allowed to regrow for approximately 1 year. Observation data was then recorded in March of 2020.

Those skilled in the art will appreciate that certain characteristics will vary with older or, conversely, younger plants. ‘WEGROW-B6’ has not been observed under all possible environmental conditions. Where dimensions, sizes, colors and other characteristics are given, it is to be understood that such characteristics are approximations or averages set forth as accurately as practicable. The phenotype of the variety may vary with variations in the environment such as season, temperature, light intensity, day length, cultural conditions and the like. Color notations are based on The Royal Horticultural Society Colour Chart, The Royal Horticultural Society, London, 2015 (sixth edition).

A botanical description of ‘WEGROW-B6’ and comparisons with the parents and most similar commercial cultivar are provided below.

-   General plant description:     -   -   Plant habit.—Deciduous tree with an upright ascending,             moderately-branching growth habit.         -   Tree crown profile.—Broad-ovate.         -   Dimensions.—The original tree grew to approximately 7.23             meters tall and 0.40 meters wide at 7 years of age.         -   Plant vigor.—Vigorous.         -   Growth rate.—Fast growing.         -   Environmental tolerances.—Cold hardy to at least minus 22             degrees Celsius; prefers well drained soils with regular             irrigation, and full sun exposure.         -   Pest and disease susceptibility or resistance.—Plants have             not been observed to be susceptible or resistant to             pathogens and pests common to Paulownia sp.         -   Propagation.—Propagation is accomplished by way of             meristematic tissue culture micropropagation.         -   Crop time.—When cultivated for timber production,             approximately eight growing seasons are needed to first             harvest and an additional two seasons for main harvest. -   Root system:     -   -   Description.—A network of fibrous, non-fleshy roots.         -   Rooting habit.—Freely branching, moderately dense, and             moderately deep in the soil profile; 4.5 to 9.0 meters deep. -   Stems:     -   -   Branching habit.—A dominant, near-vertical central main             stem, typically branched, gives rise to a strong formation             of lateral branches.         -   Main stem; dominant central leader.—Quantity — One. Attitude             — Erect; near vertical. Aspect — Generally rounded-ovate.             Diameter — 40 cm, at breast height, on an 8 year-old tree.             Strength — Very strong. Texture — Glabrous, lenticellate and             becoming progressively fissured with age. Lenticels are             irregularly elliptical to elliptical and range in size from             0.5 mm to 5.0 mm long and 1.0 to 5.0 mm wide. Color is             greyed-green, nearest to in between RHS 195A and 199D.             Color, juvenile — Greyed-Brown, nearest to a mixture of RHS             195D, 199B, 197C, and 200A; irregularly blotched and banded             with greyed-green, nearest to RHS 195A. Moderately suffused             with a mixture of green, RHS 144A, and yellow-green, RHS             146A; suffusion becomes less pronounced as the wood ages.             Color, oldest wood — Brown, nearest to a mixture of RHS             195B, 195D, 197A, 200A, 200B, 200C and 200D; irregularly             blotched and banded with greyed-green, nearest to RHS 194B;             fissures are nearest to in between yellow-green and             greyed-orange; RHS 197A, 152A and 177B.         -   Lateral branches.—Quantity primary lateral branches — 5 to             7, on average. Quantity of secondary lateral branches —             14.6, on average. Attitude — Slightly oblique, right-angle             branches, relative to the main stem. Aspect — Wide-ovate.             Diameter at breast height — 10.40 cm, on average. Diameter             at the root collar — 14.48 cm, on average. Stem strength —             Strong. Texture and luster — Glabrous, moderately glossy,             and moderately lenticellate. Lenticels are irregularly             elliptical to elliptical and range in size from 1.0 mm to             5.0 mm long and 1.0 to 4.0 mm wide; color is greyed-green,             nearest to in between RHS 193C and 195D. Color —             Greyed-green, nearest to a mixture of RHS 194C, 195A, and             197B; irregularly blotched and banded with greyed-green,             nearest to RHS 146D. Moderately suffused with a mixture of             green, RHS 144A, and yellow-green, RHS 145C. -   Foliage:     -   -   Arrangement.—Opposite.         -   Attachment.—Petiolate.         -   Division.—Simple.         -   Shape.—Wide-ovate to cordate.         -   Length.—41.6 cm, on average.         -   Width.—37.06 cm, on average.         -   Apex.—Cuspidate.         -   Base.—Cordate.         -   Margin.—Ciliate; and serrate to doubly serrate in young             plants; slightly to moderately undulated.         -   Aspect.—Flat.         -   Texture and pubescence, adaxial surface.—Glabrous, slightly             bullate, and slightly glossy.         -   Texture and pubescence, abaxial surface.—Pubescent, slightly             bullate and matte.         -   Color.—Juvenile foliage, adaxial surface — Yellow-green,             nearest to in between RHS N140D and N141C, and suffused             light blue, RHS 106D. Juvenile foliage, abaxial surface —             Yellow-green, nearest to in between RHS 143B and 143D.             Mature foliage, adaxial surface — Yellow-green, nearest to a             mixture of RHS N144A, N144B and N144C. Mature foliage,             abaxial surface — Yellow-green, nearest to in between RHS             144C and N144B.         -   Venation.—Pattern — Reticulate. Vein color, adaxial surface             — Yellow-green, nearest to RHS 142D and 144D. Vein color,             abaxial surface — Yellow-green, nearest to in between RHS             N144B and N144D.         -   Petiole.—Length — Ranging from 10.0 to 14.0 mm. Diameter —             Ranging from 0.6 to 1.0 cm. Texture, adaxial and abaxial             surfaces — Moderately pubescent. Color, adaxial and abaxial             surfaces — Yellow-green, nearest to a mixture of RHS 145B             and N144A, and suffused with yellow-green, RHS 144D.             Trichomes — Present on the abaxial surface; mostly glandular             but occasionally dendroid. -   Inflorescence:     -   -   Habit.—Large terminal thyrses; pyramidal in profile.         -   Natural flowering season.—Buds develop in late September and             into early October, Rheinbach, Germany, and remain unopened             through winter; flowers then emerge in the following spring,             in late March.         -   Attitude.—Erect.         -   Inflorescence dimensions.—Typically ranging from 16 to 25 cm             long and 14 to 20 cm wide.         -   Quantity of flowers per inflorescence.—Approximately 20             flowers and buds, with 3 to 4 flowers and buds per             peduncular branch of the inflorescence.         -   Peduncle.—Color — A mixture of RHS 170A, 170B, 171A, and             172C. Texture — Totnentose. Strength — Strong. -   Flower bud:     -   -   Shape.—Ovoid.         -   Dimensions.—1.75 cm long and 1.0 cm wide, prior to bud             break.         -   Texture.—Tomentose.         -   Bud color.—Nearest to a mixture of RHS N167A, N170A, 170B,             171A, and 172C. -   Flower:     -   -   Type and shape.—Zygomorphic; funnelform; proximal portion of             the petals are fused with five free petal lobes, distally.         -   Dimensions.—8 cm long and 4 cm wide.         -   Attitude.—Upward and outward.         -   Persistence.—Flowers persist for approximately one month.         -   Fragrance.—Mild vanilla, creamy-spice fragrance; fragrance             is stronger at night.         -   Pedicels.—Dimensions — 2.0 to 2.5 cm long and 0.8 to 1.4 cm             in diameter. Color — A mixture of RHS 170A, 170B, 171A, and             172C. Texture — Tomentose. Strength — Strong.         -   Calyx.—Calyx shape — Shallowly campanulate; sepals fused,             proximally. Dimensions — 2.8 to 3.0 cm long and 1.9 to 2.3             cm wide. Sepal lobes — Quantity of sepal lobes — Four.             Dimensions — 2.2 to 3.0 cm long and 0.5 to 0.8 cm wide at             the base. Shape — Ovate. Sepal apex — Acute. Sepal base —             Fused. Sepal margin — Entire. Sepal texture — Tomentose;             densely covered with a hairy indumentum. Sepal color, inner             surface — A mixture of RHS 166B, 166C, N167A, and N167B.             Sepal color, outer surface — A mixture of RHS 166B, 166C,             N167A, N167B.         -   Corolla.—Petal lobes — Quantity — Five. Shape of petal lobes             — Rounded. Dimensions of the lobes — 2.5 cm long and 2.5 cm             wide. Apex — Obtuse. Base — Fused at the base. Margin —             Ciliate; moderately undulated. Aspect — Moderately reflexed.             Texture, inner surface — Glabrous. Texture, outer surface —             Glabrous. Color, inner surface — White, nearest to RHS             NN155D; when viewed in a vertical plane, the upper portion             of the corolla is moderately to heavily suffused with             violet, RHS 92C, while the lower portion of the corolla is             very lightly suffused with violet, RHS 92D. Striped with             light yellow at the points of fusion of the lowermost petal             lobes, RHS 8C, when viewed in a vertical plane. Color, outer             surface — White, RHS NN155D, and very lightly suffused with             yellow, nearest to RHS 2D; when viewed in a vertical plane,             the upper portion of the corolla is moderately to heavily             suffused with violet, RHS 91C while the lower portion of the             corolla is very lightly suffused with violet, RHS 92D.             Striped with light yellow at the points of fusion of the             lowermost petal lobes, RHS 2C, when viewed in a vertical             plane. -   Reproductive organs:     -   -   Androecium.—Stamens — Four didynamous stamens, with             filaments fused to the floral tube; twisted near the base;             sparsely glandular to hairy. Stamen length — 4.0 to 5.5. cm             long, with two stamens being longer than the others.             Filament — Length — 3.5 to 4.5 cm long. Color — Nearest to a             mixture of RHS NN155A, 155D, and 157A. Anther — Shape —             Divergent; narrow. Dimensions — 6 to 10 mm long and 0.3 to             0.4 cm wide. Color — Nearest to a mixture of RHS NN155A,             155C, 155D, 156A, and 157A. Pollen — Shape — Round to             triangular; convex; spheroid; reticulate. Dimensions — 21             μm. Pollen color — Nearest to in between 2D and 4D.         -   Gynoecium.—Pistil quantity — One. Pistil length — 6.5 to 7.5             cm long. Stigma — General description — The slightly             bilobate stigma tip has a single small hole that leads to a             tubular dilated chamber at the top of the style covered in             receptive papillae. Diameter — 2.0 to 2.3 mm. Color —             Nearest to a mixture of RHS NN155A, 155C, 155D, 156A, and             157A. Style — Length — 5.5 to 6.5 cm. Color — Nearest to a             mixture of RHS NN155A, 155C, 155D, 156A, and 157A. Ovary —             General description — Bilocular. Dimensions — 2.4 cm long             and 1.0 cm wide. -   Fruit and seed:     -   -   Fruit.—General — The ovary develops into a sticky oval             capsule tapered at the apex with the remaining desiccated             style sometimes still attached. The capsule remains on the             persistent calyx, where they can last on the tree through             the rest of the year before turning woody and loculicidal             dehiscence. Shape — Oblong; elliptical. Dimensions — 4.5 to             5.5 cm long and 9.0 to 1.01 cm wide. Texture — Tomentose.             Color — Nearest to a mixture of RHS 152C, 152B, 153B, 144B,             163A, and 167A; pubescence is RHS 145D.         -   Seed.—General — The membranous and winged seeds are very             light and soft; wings gradually increase in length around             the seed. The ventral and dorsal sides of the seed are flat.             Dimension — 2 to 7 mm long and 20 to 23 mm wide. Color —             Nearest to a mixture of RHS NN155D, 8D, and 150D. Maturity             time — Autumn.

COMPARISON WITH THE PARENT PLANTS

Plants of the new cultivar ‘WEGROW-B6’ differ from the seed parent, an unnamed Paulownia elongata tree (not patented), by the following characteristics described in Table 1.

TABLE 1 Characteristic ‘WEGROW-B6’ The seed parent Growth rate of stem Slow. Intermediate. diameter. Vertical growth rate. Fast. Intermediate. Attitude of the dominant Erect. Curved. central leader.

Plants of the new cultivar ‘WEGROW-B6’ differ from the pollen parent, an unnamed Paulownia fortunei tree (not patented), by the following characteristics described in Table 2.

TABLE 2 Characteristic ‘WEGROW-B6’ The pollen parent Tree height Significantly shorter than the Significantly taller than pollen parent. ‘WEGROW-B6’. Cold hardiness. Significantly more cold hardy Much less cold hardy than the pollen parent. than ‘WEGROW-B6’. Vertical growth. Faster than the pollen Slower than parent. ‘WEGROW-B6’.

COMPARISON WITH THE MOST SIMILAR PAULOWNIA HYBRID CULTIVAR KNOWN TO THE INVENTOR

Plants of the new cultivar ‘WEGROW-B6’ differ from the closest known commercial comparator, Paulownia ‘Phoenix One’ (Community Plant Variety Rights Grant number EU 39980), in the following Characteristics described in Table 3.

TABLE 3 Characteristic ‘WEGROW-B6’ ‘Phoenix One’ Main stem girth; Slower than the Faster than rate of growth. ‘Phoenix One’. ‘WEGROW-B6’. Main stem; rate of Faster than the Slower than vertical growth. ‘Phoenix One’. ‘WEGROW-B6’. Time to flower. Early flower initiation; bud Does not flower in development is initiated in European climates. late September with flowers opening in late March of the following year. Cold hardiness. More cold hardy; to Less hardy; to minus-10 minus-22 degrees degrees Celsius. Celsius. 

That which is claimed is:
 1. A new and distinct variety of Paulownia hybrid tree named ‘WEGROW-B6’, substantially as described and illustrated herein. 